A liquid processing is performed on a substrate using liquid in a process of manufacturing a semiconductor integrated circuit or a flat panel display. In order to perform the liquid processing, a single wafer processing device is utilized which includes a rotating plate, a substrate support unit provided on a peripheral edge of the rotating plate to support an outer periphery of a substrate, a liquid supply unit which supplies liquid to the substrate supported on a substrate support unit, and a cup unit which receives the liquid supplied to the substrate and scattered due to the rotation of the substrate.
Further, the liquid processing apparatus is provided with a detection apparatus which detects the presence or absence of the substrate supported on the substrate support unit. See, for example, Japanese Patent No. 2920855.